diff --git a/nix/module-joex.nix b/nix/module-joex.nix
index a0590f81..373a6aed 100644
--- a/nix/module-joex.nix
+++ b/nix/module-joex.nix
@@ -118,6 +118,7 @@ let
         ];
       };
       working-dir = "/tmp/docspell-analysis";
+      clear-stanford-nlp-interval = "15 minutes";
     };
     processing = {
       max-due-date-years = 10;
@@ -771,6 +772,14 @@ in {
                 files.
               '';
             };
+            clear-stanford-nlp-interval = mkOption {
+              type = types.str;
+              default = defaults.text-analysis.clear-stanford-nlp-interval;
+              description = ''
+                Idle time after which the NLP caches are cleared to free
+                memory. If <= 0 clearing the cache is disabled.
+              '';
+            };
 
             regex-ner = mkOption {
               type = types.submodule({